WhatsApp seems to have similar widespread market adoption in Brasil[1] too.

[1] https://www.washingtonpost.com/world/the_americas/whatsapp-i...

Orkut too was much popular in India & Brazil, looks like these both countries have similar users.

Nah, it's just that WhatsApp is massively popular worldwide, except for China and the US.

From my limited experience, I know in India you can get a lot of SMS spam. I wonder if people migrated to whatsapp for that reason?

I think one of the bigger reasons was something the article touches upon - image sharing. Internet connections can often be sketchy, and Whatsapps compressed image sharing often ran circles around its competitors.

The other reason was the identity to phone number mapping and the ease of setting up communities with those identities.

Yet another reason was you didn't need to separately pay for a mobile data package and a SMS package anymore - WhatsApp replaced SMSes and it fit frugally into the data plan.

I know that in my circles these played a big role. Reason 1 was especially significant for my parents/older relatives since my conversations with them are not text heavy (maybe them getting used to a device to type in for casual communication is a factor) - we often share images, family photos - and WhatsApp killed it in this niche use-case.

I think the reasons are :

1. It's free ( if you already have Internet on your phone )

2. It's very easy to use and fast

3. The multimedia experience is better than MMS

4. Group chats

5. Network effects ( Some companies provide customer service through WhatsApp, your friends may already hang out in certain WhatsApp groups etc )

Unfortunately many people have to mute WhatsApp messages because they may be in a family group, getting too many messages and it may be considered rude to leave